Environmental Path 1 Flashcards
What are xenobiotics
exogenous chemicals in the environment in air, water, food, and soil that may be absorbed into the body through inhalation, ingestion, and skin contact
How do we deal with xenobiotics and what can this lead to?
P450 system catalyzes reactions that detoxify (inactivate) xenobiotics into water solubale products, or less commonly activate them into toxic metabolites. These reactions can produce ROS leading to cellular damage
How do we eliminate xenobiotics from the body?
Eliminated in urine/feces, air, or can accumulate in bone/fat
What makes xenobiotics so good at traversing the body
Can act at site of entry or site it’s distributed to. Most are lipophilic so can travel through blood with lipoprotein and easily traverse cell membranes.
Discuss toxic metabolites and what stages of metabolism they fall into
Drugs, solvents and xenobiotics are metabolized into either water soluble (inactive/detoxified) products or into toxic metabolites.
2 phases of metabolism:
Phase 1: Hydrolysis, oxidation or reduction reactions.
Phase 2: Production of water soluble compounds through glucuronidation, sulfation, methylation and conjugation with glutathione
What makes up smog?
EPA monitors levels smog, which is composed of sulfur dioxide, carbon monoxide, ozone, nitrogen dioxide, lead and particulate matter.
These pollutants decrease lung function
Ozone - In Healthy adults and children Nitrogen dioxide - In asthmatics Sulfur Dioxide - In asthmatics Acid aerosols - In asthmatics Particulates - In those with chronic lung or heart disease
These pollutants increase airway reactivity
Ozone - In Healthy people
Nitrogen Dioxide - In healthy people
These pollutants cause lung inflammation
Ozone - in healthy people
These pollutants increase airway infections
Nitrogen Dioxide - Children
Acid Aerosols - Children
Particulates - Children
These pollutants alter mucocilliary clearence
Acid aerosols in healthy folks
Where do we find ozone and how is it made?
Made by interaction between UV radiation and O2 in stratosphere, accumulates in the ozone layer 10-30 miles above earth surface.
Why has ozone been reducing?
Has been shrinking as a result of chlorofluorocarbon gases in ACs, refrigerators etc. Montreal protocol made series of agreements to phase out chlorofluorocarbon gas use by 2020. This is working.
Discuss ground level ozone and what we worry about
Ground level ozone: gas made by reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight.
These chemicals come from industrial emissions and car exhaust. Ozone toxicity a/w ROS formation that causes inflammation in respiratory epithelial cells.
What happens when ozone meets another pollutant?
Ozone can combine with other pollutants such as sulfur dioxide (from burning coal/oil, copper smelting and paper mill byproducts) to make sulfuric acid or sulfuric trioxide. This causes burning of nose and throat, dyspnea and asthma in susceptible individuals.
Particulate matter (soot) comes from what? What size do we worry about the most?
Comes from coal and oil burning power plants and, diesel exhaust. Most harmful particles are less than ten micrometers in diameter which can be inhaled through alveoli and cause inflammation. Larger than 10 are caught in nose or mucociliary epithelium.
Describe Carbon monoxide (smell, appearance)
Odorless, colorless, non irritating gas
Discuss the pathophysiology of Carbon monoxide
Path: Hgb has a 200x greater affinity for CO than O2. Carboxyhemoglobin can’t carry O2.
Carboxyhemoglobin is very stable and chronic low-level CO exposure can lead to carboxyhemoglobin accumulation.
Symptoms of carbon monoxide poisoning
20-30% carboxyhemoglobin→ systemic hypoxia.
60-70% carboxyhemoglobin→ death/unconsciousness.
